I've been reading the rules and can't seem to find if there was a clause for allowing stripped interior to allow for roll cage. Can anyone shed light on if I can run in street modified FWD if the car is stripped interior to facilitate roll cage. the logic is that 200lb+ cage is heavier than the plastic interior pieces.

You can only strip from behind the front seats or something - and even then, I think it's just rear seats? Been a while since I've done SM, but you can cut the interior to fit a cage, but you can't completely remove it.